The Ailanthus class were a group of 35 wooden-hulled net laying ships of the United States Navy built during World War II as part of the huge building programs of late 1941 and early 1942 for small patrol and mine warfare vessels.
Five of the class were transferred to the British Royal Navy under Lend-Lease, and another five were converted while at their shipyards into Auxiliary Fleet Tugs, the ATA-214-class.
In September 1944, as a trial, a third 20 mm gun was installed on a small elevated platform mounted on a pedestal between the bridge and the smokestack on Terebinth (AN-59), but it was found that the arc of fire was restricted, that the platform was too hot to permit the storage of ready ammunition, and that the gun crew became ill from engine fumes.
Instead, two additional single 20 mm guns were installed at the after end of the deckhouse on AN 39-63 and 66-69.
[1] Two ships of the class were lost during the war; In early 1946 six of the ships, Cliffrose (AN-42), Cinnamon (AN-50), Silverbell (AN-51), Torchwood (AN-55), Catclaw (AN-60), and Shellbark (AN-67), were transferred to the Republic of China's Maritime Customs Service at Shanghai, while the remainder were disposed of in 1947 in a Maritime Commission sales program for small vessels.